Enhancing rigour in the validation of patient reported outcome measures (PROMs): bridging linguistic and psychometric testing

Evidence is drawn from a study to develop a Welsh language version of the Beck Depression Inventory-II (BDI-II) and investigate its psychometric properties. The BDI-II was translated into Welsh then administered to Welsh-speaking university students (n？=？115) and patients with depression (n？=？37) concurrent with the English BDI-II, and alongside other established depression and quality of life measures. A Welsh version of the BDI-II was produced that, on administration, showed conceptual equivalence with the original measure; high internal consistency reliability (Cronbach’s alpha？=？0.90; 0.96); item homogeneity; adequate correlation with the English BDI-II (r？=？0.96; 0.94) and additional measures; and a two-factor structure with one overriding dimension. Nevertheless, in the student sample, the Welsh version showed a significantly lower overall mean than the English (p？=？0.002); and significant differences in six mean item scores. This prompted a review and refinement of the translated measure.Exploring potential sources of bias in translated measures represents a critical step in the translation-validation process, which until now has been largely underutilised. This paper offers important findings that inform advanced methods of cross-cultural validation of PROMs.